Joe McCarthy was a senator who, in the period after WW II went on a hunt (often called, perhaps erroneously, a "witchhunt) for Americans who had ties to the Communist Party which was then seen as a real threat to the United States. He ruthlessly went after individuals, many powerful people in Washington and Hollywood, who he alleged had ties to the Party. He was disgraced and dismissed, even though history has indicated that he was correct about some/many of these individuals (there is more information to be divulged).
Miller set out to discredit McCarthy, and he did it with two plays: he wrote "The Crucible" and adapted Ibsen's "An Enemy of the People" for the modern stage. The Crucible presents the "heroic" figure of Proctor who represents all the individuals that Miller thought were being falsely accused and who defended their honor in the face these accusations. The same scenario presents itself in "An Enemy of the People" where the heroic Doctor Stockmann finds that the theraputic springs that are the source of the town's income are harmful and refuses to back off his assertion under the pressure of the town's people.
Both these plays, written/edited in the early 1950's, clearly support Miller's view that the heroic individual must stand up for the truth in the face of attempts to destroy the truth and are a response to the pressure that McCarthy brought on many of his friends.
This is a fantastic question. Miller wrote "The Crucible" during the McCarthy era. The play is about a man, John Proctor, who does not sacrifice his name, his dignity, in order to save his own life. Proctor does not point the finger at somebody else in order to avoid hardship.
What is most interesting is that Arthur Miller himself was called before the House on Unamerican Activities Committee and asked to point the finger at communists in Miller's field. He, like Proctor in his play, refused to do so.
Miller is one of my personal heroes because of this. It is a great example of life imitating art.